In the production of polyurethane or isocyanurate foams, it is often necessary to add aggregates in order to obtain certain properties in the finished product or in order to be able to utilize waste or to lower the cost of the materials. The aggregates used to lower cost include fillers such as cement, lime, chalk, gypsum, barium sulphate or powdered foam resin produced from size reduced foam waste. The aggregates used for increasing the mechanical strength or fire resistance include, in particular, fibrous materials such as staple glass fibers, ground glass fibers, carbon fibers or other fibers based on inorganic or organic materials. The introduction of the aggregate into the reaction mixture has already been attempted by a wide variety of methods. Difficulties lie in accurate metering in proportion to the reactants, in the avoidance of blockages in the pipes and in the unwanted introduction of air with the bulky aggregates. Uncontrolled introduction of air interferes with the foaming reaction and, in particular, the foam structure of the finished product is impaired by the inclusion of substantial quantities of air.
The object of this invention is a process and an apparatus for the production of a reaction mixture containing aggregates from which fault free finished products can subsequently be produced.